The present invention relates to a method of inspecting an array substrate, and particularly to a method of inspecting an array substrate being capable of reducing connections of an outer circuit in number.
In a display device, for example, in a liquid crystal display device using a polycrystalline silicon TFT, a portion of the signal line drive circuit and the gate line drive circuit are formed integrally on an array substrate. In this case, a portion of the signal line drive circuit, for example, the D/A converter circuit is mounted outside the substrate. The liquid crystal display device formed like this is capable of reducing connection wires between the array substrate and an outer circuit substantially in comparison to a liquid crystal display device using an amorphous silicon TFT.
An open defect means a line including some breaking points in the line. A short circuit means a line including some connecting points to another line.
In a display device as described above, when inspecting a short circuit between adjacent signal lines, an inspection pad is mounted on each signal line, an inspection circuit probe is connected to this pad, continuity between adjacent signal lines is inspected, and the short circuit between both signal lines is detected in case of continuity being established between them.
Moreover, in a display device as described above, when inspecting breaking of a signal line, inspection pads are mounted at both ends of each signal line, inspection circuit probes are connected to these pads, continuity through the signal lines is inspected, and breaking of wire is detected in case of no continuity is established through the signal line.
However, in order to inspect a short circuit between the signal lines, not only inspection pads as many as the signal lines, but also inspection probes corresponding to the number of pads are required. Moreover, in order to inspect breaking of the signal lines, not only inspection pads two times the number of the signal lines, but also inspection probes corresponding to the number of pads are required.
As described above, since a number of inspections probes are required, the cost of the inspection circuit is increased and there is also a problem of complicated maintenance.
Moreover, when highly fine pixels involve increased signal lines, it becomes difficult to secure space for mounting inspection pads, and the advantage of using a polycrystalline silicon TFT is reduced.